International Statistical Review (2005),73, 2, 239–240, Printed in Wales by Cambrian Printersc© International Statistical Institute

Discussant: Donald A. Dawson

Carleton University, Ottawa, Canada. E-mail: ddawson@math.carleton.ca

1 Introduction

The paper of El-Shaarawi and Teugels explains the importance of environmental statistics andgives a brief indication of three major problem areas, namely, natural disasters, water quality andclimate change. The rising concern worldwide over environmental issues has led to many nationaland international initiatives to develop the statistical basis on which to identify and quantify risks.

As the authors emphasize, environmental issues are inherently complex and interrelated. In orderfor informed policies to be developed, unbiased and reliable statistical data and modeling is essen-tial. There are three major challenges that must be addressed by statisticians in dealing with anyenvironmental issue:

� formulation of the essential questions that should be addressed� development of the appropriate statistical methodology� communication of the results to both policy makers and the general population.

Educating policy makers on sound statistical principles and standards is an essential part of this,to counter the all too common use of questionable statistics used to delay or prevent the introductionof needed environmental policies.

2 Statistical Challenges Coming from Environmental Problems

The authors describe a number of environmental issues that require a wide range of statisticalmethodologies. Variability at all spatial and temporal scales is inherent in the global environment.Experimental design is a powerful tool for environmental risk assessment but, in many cases suchas climate change, controlled experimentation is not possible. Risk assessment and managementin environmental problems requires the development of more realistic models for extreme eventsthat include spatial and spatio-temporal aspects. Spatial data analysis is an area of statistics that hasdeveloped rapidly in response to these challenges and has produced new methodologies and compu-tational tools. These advances together with the use of geographic information systems (GIS) provideimportant tools for remote sensing of the earth and climate modeling. A large amount of informationand software for spatial data analysis now exists (seee.g. http � ��www�statistical�org�).

Further challenges exist in developing methodologies to handle spatio-temporal data such as arisein water quality management. The challenge involves the analysis of massive data sets and theattendant issues of computational complexity. The authors point out that research is needed to finda wider class of valid spatial and temporal covariance matrices. In addition, phenomena involvinglong memory and heavy tails arise in environmental problems. The search for appropriate modelsfor these in the spatio-temporal setting raises difficult mathematical and computational problems. Inthe study of climate change, the inherent non-stationarities and non-linearities in the spatio-temporalstructure make the problem of analyzing extreme events and clustering in space and time a difficultmathematical challenge.

240 D.A. DAWSON

3 Role of Statistical Organizations

The authors discuss the role of statistical organizations in promoting environmental statistics. InparticularThe International Environmetrics Society (TIES) has made an important contribution tothis field and publishes the journalEnvironmetrics. TheISI Committee on Statistics and the Environ-ment has contributed to this and the recent initiative to have TIES become an ISI Section is a verywelcome development that will serve well both the international efforts to promote environmentalstatistics and the ISI’s mission. There are also important opportunities for cooperation between thedifferent ISI sections as well as with other organizations. For example the International Workshop“Statistical Science and Environmental Policy: Possible Interactions” held in Kolkata, January 2000was co-sponsored by the Bernoulli Society and the Indian Statistical Institute. The proceedings ofthis workshop describe technical developments in a number of environmental areas.

4 Conclusion

To conclude, I would like to thank Professors El-Shaarawi and Teugels for their paper reviewingsome major outlines of this important application area of statistics.

Related Reading

Ghosh, A.K., Ghosh, J.K. & Mukhopadhyay, B. (Eds.) (2003).Sustainable Environments, A Statistical Analysis. OxfordUniversity Press.

United Nations Department of International Economic and Social Affairs (1991). Concepts and methods of environmentstatistics: statistics of the natural environment, Studies in Methods, series F, No. 57.

[Received March 2005, accepted May 2005]